The project brings residents together for indoor table top gardening sessions and trains care home staff to carry on the gardening programme once the project ends.
Thrive's horticultural therapist Daron Gardner is heading up the training programme.
At one care home in Basingstoke, the residents who have been gardening with Thrive are already reaping the benefits.
Charmain Jarvis, activities co-ordinator at Oakridge House which cares for 90 residents, said: "We're really enjoying getting our hands dirty. The residents who are taking part are thoroughly enjoying being able to garden as many miss their own garden at home so much.
"The indoor sessions with Thrive have proved that it is an easy and straightforward activity to do when you have the knowledge and support.
"It can be a very focussed task with residents concentrating on something they enjoy, exercising their hands and being mentally and physically stimulated. We've been able to enjoy conversations about fields of bluebells, flowers that were in their wedding bouquets, the scent of certain flowers like lavender and what memories they bring.
"And we have also noticed that some of our residents enjoy coming to the session but are very happy just sitting watching other plant seeds and pot on, listening to the conversations. Now we are approaching summer I hope we can move into the garden outside."
Thrive's Gardner says the residents who are coming to the gardening sessions are getting more and more invigorated each week.
"It is great to see people wanting to join in the group gardening sessions, which not only helps with their general health and wellbeing, but offers a sense of empowerment and independence, particularly for those that previously enjoyed gardening, but felt it was an interest they had to give up," he said.
"Gardening enables residents to enjoy a social activity that provides meaning and purpose whilst positively contributing to their physical and psychological wellbeing."
The Gardening Together project, funded by Comic Relief and The Rayne Foundation, was born out of a report which highlighted "the experience of emotional neglect resulting from feeling isolated, ignored or powerless" for some older people in care homes.
The Panicoa (Preventing Abuse and Neglect in Institutional Care of Older Adults) report said that one of the weakest areas of care performance was in "the social engagement of older people and their need for meaning and purpose in their life".
It also stated that many staff experience work-related stress and emotional "burn out", the overall level of job satisfaction for care assistants is low and whilst staff were keen to develop their skills and capabilities, the opportunities to do so were limited.
Care home residents and staff take part in this gardening activity together, working with Daron to learn about plants and how to care for them.
Kathryn Rossiter, chief executive at Thrive, said: "Gardening Together aims to help people stay healthy for longer and live fuller lives after they leave their own homes.
"As people leave their homes they may feel vulnerable as they lose their independence. Gardening can add structure to their lives and give some independence back. It has been shown to improve residents' health and wellbeing, and gives them a sense of empowerment.
"The changes people face as they age impacts on their physical, emotional and cognitive wellbeing and they can become more socially isolated. Group gardening is a therapeutic way to address these issues, nurturing social interaction, communication and team working.
"As well as benefiting residents, this will have a positive impact in the care sector, and will support care home staff to provide meaningful and beneficial activities to residents through gardening.
"We want staff to gain more job satisfaction and feel more empowered to help residents live a more fulfilled life. There is an extra positive benefit for the care home sector, as residents and staff take pride in their surrounding knowing that they have contributed to the environment in which they live and work."